How to check permission of a file or path?


Hello,

I know this is possible by "stat" command or  "ls"  command but I'm looking for a command to return me if $USER (current user) has  privilege or permission to a specific /dir1/dir2/a_file

1) Let's say user1 runs script1
2) user1 has access to some paths and no access to some others
3) I need a command to return a  true/false value or anything to check it in my script befoer following a procedure.

Thanks
akohanAsked:
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ozoConnect With a Mentor Commented:
#!/bin/bash
READ=`perl -e 'print 0+-r "/dir1/dir2/a_file"'`
WRITE=`perl -e 'print 0+-w "/dir1/dir2/a_file"'`
EXECUTE=`perl -e 'print 0+-x "/dir1/dir2/a_file"'`
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ozoCommented:
perl -e 'print 0+-r "/dir1/dir2/a_file"'
perl -e 'print 0+-w "/dir1/dir2/a_file"'
perl -e 'print 0+-x "/dir1/dir2/a_file"'
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akohanAuthor Commented:

Thanks you so much but it has to be in bash.

Thanks again for your resonse.
AkOHAN

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amit_gConnect With a Mentor Commented:
stat -c%a TheFile

would return you the octal access rights for example 644 but that might need more tests. You could do

if [ -r TheFile ]
then
    echo file exists and is readable.
fi

if [ -w TheFile ]
then
    echo file exists and is writable.
fi

if [ -x TheFile ]
then
    echo file exists and is executable.
fi

if [ -d TheFile ]
then
    echo file exists and is a directory.
fi

if [ -d TheFile -a -r TheFile ]
then
    echo file exists and is a directory and is redable.
fi

if [ -d TheFile -a -w TheFile ]
then
    echo file exists and is a directory and is writable.
fi

if [ -d TheFile -a -x TheFile ]
then
    echo file exists and is a directory and is executable i.e. can do cd to it.
fi

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MysidiaConnect With a Mentor Commented:
If  Kpathsea's installed, there is an access command...

if  [ access -rw /path/to/file ] ; do
  blah blah
done

Assuming 'access' is in PATH, usually it's in some weird place like /usr/share/texmf/bin/access
The access command uses the access() system call, shell test checks permission bits.

The difference matters if the filesystem is mounted read-only.

if [ -w TheFile ] ; then
    echo file exists and is writable.
fi

Will report that the file is writable, if you match write permissions, even if the filesystem the file sits on happens to be read-only (and writing would be denied based on that).
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